OpenEuphoria

External Modem Emulator

• Posted by Ben Logan <wbljr79 at HOTMAIL.COM> Jan 26, 2000
• 559 views

Thanks, Bernie, and Jeff.  I was able to get the com ports working.

Here's what I'm trying to accomplish:

I have two computers on the same desk; a P166 with a controller-less modem
(winmodem--BLEHCK), and a 486 with a 14.4k modem.  I've recently installed
Linux (Redhat 5.2) on the P166, and it won't work with the winmodem.  (I'm
still running Windows on the P166, I'm just playing around with Linux.)

So...I was thinking...what if I could redirect the input and output on the
486 so that anything coming in thru COM1 is sent out COM2, and anything
coming in thru COM2 is sent out COM1.  Now, assuming that the modem in the
486 is on COM2, if I connect the two computers via a serial cable (COM1 on
486 to COM1 on P166) then the P166 will be fooled into thinking that it's
got an external modem.  (I'm speculating, not stating fact.)

So far, it seems to be working.  I can control the 486's modem from the P166
in Windows or Linux.  Some things don't seem to work properly, but I think
it's probably because it's so slow.  One thing I don't understand is that it
will only work if I set flow control to software...it won't work on
hardware.

Now that I've explained what I'm trying to do, I was wondering if anyone can
tell me how to make it work better--or tell me that there's no chance of
getting it to work properly.  I've included the program I wrote.  It runs on
the 486.

-------------------MEMU.EX-----------------------
--Modem emulator...fools computer on other end of serial cable, into
thinking
--it owns an external modem.

--Anything that comes in com2 is sent out com1, and anything that comes in
--com1 is sent out com2.
--Some concepts are taken from E-TERM.EX--Thanks to PJB Systems
--Pressing any key breaks out of the program.

without type_check

include serial.e

integer key,data,rcnt
sequence rBuffer    rBuffer = {}

clear_screen()
puts(1,"Modem Emulator in operation...press a key to terminate...")

SetPortBPDS(1,19200,0,8,1)  --Configure the ports
SetPortBPDS(2,19200,0,8,1)

rcnt = 0
key = -1
while key < 0 do
    data = GetSerialByte(2)  --See if modem has sent any data
    if data > 0 then
        rBuffer &= data  --Yes, so put it in buffer
        rcnt = 200   --This must be 200 in order not to lose data
    else
        rcnt = rcnt -1
    end if
    if rcnt < 1 then
        rcnt = 0
        key = get_key()   --If user has pressed a key, then exit prog
        if length(rBuffer) > 0 then   --If there's anything in buffer,
            for i = 1 to length(rBuffer) do --Send it out
                SendSerialByte(1,rBuffer[i]) --com1
            end for
            rBuffer = {}  --Empty the buffer
        end if
        data = GetSerialByte(1) --Get data from com1 (remote 'puter)
        if data > 0 then    --If any data was waiting,
            SendSerialByte(2,data) --send it to modem
        end if
    end if
end while
puts(1,"\n\nDone.\n")
-------------------------------------------------

Thanks in advance,

Ben

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